Actor Christopher Meloni tells us how he alternates between workouts like yoga and CrossFit to stay in shape on and off the sets of projects including "Law and Order: SVU" and "Man of Steel."

“When I was in eighth grade, I got those little plastic weights with sand inside them [for Christmas],” says Christopher Meloni, the star of four new films in 2013, including the highly anticipated Man of Steel. And since the day he unwrapped that gift, the former construction worker, bouncer, and personal trainer has never looked back.

“I feel as though I transitioned from the Arnold workout to the Navy SEAL workout,” says Meloni, who’s also into “crossfit-type stuff, using asymmetrical weights and straps to really work on stabilizing muscles.”

The actor’s workouts begin with the things he enjoys least—cardio and ab work (although currently, he’s also performing demanding rehabilitation exercises [see below] with a physical therapist to recover from a shoulder injury). From there, he focuses on “the bigger muscle groups,” he says, “and I usually sort things”— like shoulders and arms one day, chest and back another, and legs the next.

In previous years, Meloni would put his body through 90-minute workouts, attempting to lift the heaviest weights possible. Today, his weight-room regimen consists of a jam-packed hour that extends to 90 minutes only on the days he tacks on an extra treadmill session. "The workouts are fast and intense," he says—he prefers to “hit it and quit it” while “targeting exactly the muscle group I want to fire.”

That said, it takes more than weight training to sustain the level of fitness Meloni’s enjoyed throughout his career. At least five days a week, the actor also rotates activities like martial arts, basketball, football, yoga, and waterskiing into his training regimen— otherwise “the muscles lose their communication with one another,” he says. Diet plays a big role, too. “It’s impossible to fuel and repair the machine if you don’t eat correctly,” says Meloni, who starts each day with egg whites and oatmeal, followed throughout the day by three to four more meals crafted around rotations of vegetables, chicken, and fish.

It’s this commitment to diet and exercise that’s continually enabled Meloni to reinvent and reshape himself into the image of the characters he takes on. When playing Law & Order: SVU’s Elliot Stabler, he “packed on like 20 pounds” to match his vision of the character, he says. Conversely, to play baseball legend Leo Durocher in the upcoming movie 42, he says he “tried to stay slim, and not get too bulky.” For his role as Colonel Hardy in Man of Steel, Meloni says he helped craft a meticulous character biography, and stayed on his workout regimen to ensure he “looked and felt like a military guy.” It’s discipline like this that’s made him a success in a notoriously tough industry.

Even after 25 years in the business, Meloni says he’s “always looking to get better.” With such a conscientious approach to fitness and nutrition, we’re confident he will.